wilson



mlems J. E. WILSON. SCREW-PROPULSION.

Eaten-ted Now; 9, 1875.

Wilma/(raw.

@WWM

women "Wrench, or BEA-ZQfBi-ih, cronies.

Specification forming l. do hereby declare the following to be a full, 1

clear", and exact description of the some, reference being had tothe accompanying drew ings, inehing a. port of this specification, in Whifill-- Figure 1 represents a side View, partly in section, of e hoot or vessel with thejpropeller in Question attached. Fig, 2 represents explnn of the under side thereof.

My invention consists in the combination of a, a rcrew-propeller having; 21 graduated pitch of ihi'threari or blades i'roni thei'ront toward the rear of the vessel, with a. recess, box, or chamber, having a graduated or enlarged area from its front toward its; rezizy-ns willhe explained. v H

Arepresentn the hull ofn boat or veesel he ring a Yslmped even heel, B. ,In the'after port or stern of the hull and between the forks or branches of the heel, is a chrunhezg'a, which inclines upward from the junction of frlgc branches with the stern of the, heel, so as to enlarge the area or writer-wary of said chom- :laer from its front, toward its rear end, which in opexnne is also its under side. 0 is n screw-propeller, hung, end revolving in the chamber a. p

The propeller is constructed as follower Upon a central shaft, 5, is constructed the screw or threeuln o, thrnpitch' of which in gradnull spread from i'roiii; to rear, so as to cor-' reepondingiyenlarge the wager-why between j-eheni from front to rear.

The object of the spreading of the screw from front tower is that the succeeding threads or coils shall not work in the broken Water of the preceding thread, coil, or turn of the screw, it being well known that a propeller working in broken writer has very little hold upon such water, and consequently loses much of its propelling force.

The graduated spread of the ecrew should be from twenty-five to thirty per cent. in crease; or, ey in a propeller of info and onehalf feet in diameter the space between the first two turns of the thread or screw may be four and three-quarter feet, the ncxt space five and oneqnarter feet, the next six and one-half feet, and er m of Letters Potent No. flfi'ie 'fi il dated. November 9, 1875 application riled October 15,1875.

This proportion I have found answers wen;

but I may change it without departing from" the characteristic feature of this part of my invention.

The'chamher a. is enlarged in areo from front to rear, so that as the vessel settles by th'e' stern, by the raising of the how, which I occurs in loading the vessel, the rear of the screw will have abundant clearance or waterwny, so as not to impede the The object attained by the combination of or continnonsly-cxpnminrg screw-thread with a, coniinnonely-expanding chamber is twofold:

notion. of the screw.

first, that the succeeding turn of the'thrend' may not turn inthe whirl erected by the preceding turn; 01311] other words, that every portion of the thread may worlc in differentlymoving water, orwnternot broken np-hy the preceding thread into c whirl corresponding 'withthe next thread, and that the chamber or water-way may furnish the requisite voi- -n nie of were! i'o the propeller, which receives and throws'it ofi' ntecontinnous y To. gle in relation to the shaft.

. The shaft 1) passes thronghe packed henr ing; in the bottoin of the hull, as shown, end

cntende into the hold oi the vessel, where the engine and driving-go 1r are placed.

Two rudders, d 0, may be used, one at each termination of the. fork-nor branches of the heel. These rndclerearc hang to sepnrnie poets f, which are-linked together by their crn-nhs or hhns by e conplinmg, no thnthoth may he movedfitogethcr. This ennhlesthc local; to be readily and easily steered in naJr-' row, winding, and shallow anyone; and the Q branch heels may be plated with iron or other metal to protect them and the propeller hc- I tween them,

The screw mny he constructed-with single or double thread in, builder. v

' Having thus fully described my invention, what lie-lain is-- In combination with a screw-propeller hering; a graduelly-enlerged or spread pitch or thread from front to rear, the chemher a he in gincreased cleairneiss of waf r-W1; fr? one the option of the to rear, as and for the pnrpoeo described and represented, 

